Powerful signals point to a long period of sub-par growth. The huge backlog of unsold homes suggests house prices have further to fall -- by around 20% going by housing futures. Lower house prices will force Americans to spend less and save more -- a process that has hardly started. They will also spread the mortgage mess well beyond subprime borrowers, which would lead to greater financial losses.

A new study finds that, on measures from capital inflows to asset-price rises, the build-up to America's mortgage crisis looks eerily like earlier financial crises in rich countries. The parallels are not perfect, but their message is that whether or not the economy falls into an official recession, it will probably stay weak for longer than many now expect.

America faces a long, hard slog.